學術出版;;Publications

Permanent URI for this communityhdl:11536/1

收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

Browse

🏛️國立陽明交通大學機構典藏

Search Results

Now showing 1 - 10 of 13

Crystal phase control in self-catalyzed InSb nanowires using basic growth parameter V/III ratio
(2019-09-15)
Anandan, Deepak
;
Nagarajan, Venkatesan
;
Kakkerla, Ramesh Kumar
;
Yu, Hung Wei
;
Ko, Hua Lun
In this work, the influence of V/III ratio on self-catalyzed InSb nanowire (NW) crystal structure is investigated using metal organic chemical vapor deposition. The effective balance of V/III ratio determines the change of InSb NW crystal structure from zincblende to wurtzite. Particularly, as group-V molar flow varies from 6.4 x 10(-5) to 8.0 x 10(-5) mol/min, wurtzite segment length of InSb NW increases from 16 +/- 9 nm to 89 +/- 9 nm, whereas zincblende crystal phase is observed for other molar flows. We interpret the observed phase transition to a lower surface energy of In-Sb alloy droplet than pure In-droplet, which makes triple phase line nucleation energetically favorable. This study gives insight on single growth parameter (V/III ratio) change to the InSb NW crystal control, such a technique is essential to selectively tune the crystal phase of single NW for various applications.
Characteristics of a-plane GaN with the SiNx insertion layer grown by metal-organic chemical vapor deposition
(2008-11-15)
Ko, T. S.
;
Wang, T. C.
;
Huang, H. M.
;
Chen, J. R.
;
Chen, H. G.
We utilized in-situ-grown SiNx insertion layers to mitigate part of dislocations stretching in nonpolar a-plane GaN films using metal-organic chemical vapor deposition. Both X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements revealed that better crystal quality and smoother surface could be obtained when the in-situ SiNx layer was inserted closer to the r-plane sapphire substrate and indicated that the in-situ SiNx insertion layer could suppress dislocations caused by lattice mismatch between the sapphire and epitaxial layers. In addition, photoluminescence and cathodoluminescence measurements confirmed the effect of the in-situ SiNx insertion layer on the optical properties of the improved a-plane GaN thin film, which is consistent with the XRD and AFM analyses and suggested reduction in the density of nonradiative centers. (C) 2008 Elsevier B.V. All rights reserved.
Structural and electrical properties analysis of InAlGaN/GaN heterostructures grown at elevated temperatures by MOCVD
(2018-11-01)
Lumbantoruan, Franky
;
Zheng, Xia-Xi
;
Huang, Jian-Hao
;
Huang, Ren-Yao
;
Mangasa, Firman
We report the effects of the growth temperature on the structural and electrical properties of the InAlGaN/GaN heterostructures grown on c-plane sapphire substrates. X-ray Photoelectron Spectroscopy and Atomic Force Microscopy measurements results indicate that the InAlGaN layer properties is strongly dependent on the growth temperature. It is observed that the Gallium incorporation increases with the increase of the growth temperature. Meanwhile, the surface roughness decreases from 0.49 nm to 0.34 nm with the increase of growth temperature. The variation of structural properties, composition and surface morphology influences the transport properties of the InAlGaN/GaN heterostructures. High 2DEG electron density, low sheet resistance and good C-V response with a steep slope for InAlGaN/GaN HEMT were achieved at an optimized growth temperature window between 900 degrees C and 950 degrees C.
Growth of foreign-catalyst-free vertical InAs/InSb heterostructure nanowires on Si (111) substrate by MOCVD
(2019-01-15)
Anandan, Deepak
;
Kakkerla, Ramesh Kumar
;
Yu, Hung Wei
;
Ko, Hua Lun
;
Nagarajan, Venkatesan
In this study, growth of Au-free InAs/InSb vertical heterostructure (HS) nanowires (NWs) on highly lattice mismatched Si (1 1 1) substrate by metal organic chemical vapor deposition (MOCVD) is demonstrated. Careful selections of InSb growth parameters lead to In-rich growth regime such that direct impingement of growth precursors on top of grown InAs NW (self-assembled) stems result in axial InSb HSs nucleation on InAs stems. The observed indium (In) droplet on InSb HS NW tip shows that InSb HS growth followed a self-catalyzed growth mechanism. InSb HS axial growth rate and morphology are controlled by growth temperature and growth time. A small change in the growth parameters significantly affects In particle accumulation, particle size and its chemical composition, and thus affects the InSb nucleation on the stem. Especially, it is found that (i) growth time of less 10 min yields vertical InSb HS NW on the top of the InAs stem, (ii) as the growth time increases above 10 min, the growth turned to be InSb wrapped InAs/InSb core-shell HS due to coaxial lateral growth. High resolution transmission electron microscopy (HRTEM) study reveals that all the InSb HSs exhibit pure zinc-blende (ZB) crystal structure. The results presented here provide significant guidelines for external catalyst-free InAs/InSb HS NW growth using MOCVD on silicon (Si) substrate for various optoelectronics and electronics applications.
Temperature effect on the growth of Au-free InAs and InAs/GaSb heterostructure nanowires on Si substrate by MOCVD
(2018-05-15)
Kakkerla, Ramesh Kumar
;
Anandan, Deepak
;
Hsiao, Chih-Jen
;
Yu, Hung Wei
;
Singh, Sankalp Kumar
We demonstrate the growth of vertically aligned Au-free InAs and InAs/GaSb heterostructure nanowires on Si (1 1 1) substrate by Metal Organic Chemical Vapor Deposition (MOCVD). The effect of growth temperature on the morphology and growth rate of the InAs and InAs/GaSb heterostructure nanowires (NWs) is investigated. Control over diameter and length of the InAs NWs and the GaSb shell thickness was achieved by using growth temperature. As the GaSb growth temperature increase, GaSb radial growth rate increases due to the increase in alkyl decomposition at the substrate surface. Diffusivity of the adatoms increases as the GaSb growth temperature increase which results in tapered GaSb shell growth. Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) measurements revealed that the morphology and shell thickness can be tuned by the growth temperature. Electron microscopy also shows the formation of GaSb both in radial and axial directions outside the InAs NW core can be controlled by the growth temperature. This study demonstrates the control over InAs NWs growth and the GaSb shell thickness can be achieved through proper growth temperature control, such technique is essential for the growth of nanowire for future nano electronic devices, such as Tunnel FET. (C) 2018 Elsevier B.V. All rights reserved.
Interruption-free growth of 10 mu m-thick GaN film prepared on sputtered AlN/PSS template by hydride vapor phase epitaxy
(2015-09-15)
Chen, Y. A.
;
Kuo, C. H.
;
Wu, J. P.
;
Chang, C. W.
;
照明與能源光電研究所
GaN films (10 mu m-thick) of high crystalline quality were prepared on sputtered AlN/PSS template by hydride vapor phase epitaxy (HVPE). By introducing the two-step growth method into HVPE, one can reduce the steps in the procedure, realize uninterrupted growth, and improve the crystal quality of the films. The effects of initial GaN growth on the AlN/PSS template by HVPE were also investigated. In this study, 10 mu m-thick GaN films prepared on sputtered AlN/PSS template by HVPE showed improved crystal quality using X-ray diffraction and etching pits density. Compared with conventional undoped GaN film grown by metal organic chemical vapor deposition, the full width at half maximum of the (0 0 2) and (1 0 2) peaks of GaN decreased from 450 arcsec to 290 arcsec and from 376 arcsec to 344 arcsec, respectively. Transmission electron microscopy results showed that the gaps observed between the convex regions would eventually turn into dislocations during coalescence, because the number of dislocations increased with the number of gaps observed between the convex regions after step-1 growth. (C) 2015 Elsevier B.V. All rights reserved
Hydrogen etching on the surface of GaN for producing patterned structures
(2011-01-01)
Yeh, Yen-Hsien
;
Chen, Kuei-Ming
;
Wu, Yin-Hao
;
Hsu, Ying-Chia
;
Lee, Wei-I
The morphology of GaN etched in hydrogen atmosphere is investigated. It is found that GaN surfaces have different profiles after being etched at different pressures. The profile resembles a surface that has been decorated with columns or mooring posts at high pressure and with deep cavities at low pressure. Etch pit density (EPD) experiment shows all dislocations have been etched to form cavities at low pressure, but not all the cavities result from etched dislocations. A model has been developed to explain the mechanism of H(2) etching. Patterned structure with a flat surface and porous inside has been produced by two-step etching which is designed according to the model. (C) 2010 Elsevier B.V. All rights reserved.
Long-wavelength electroluminescence of InGaAs-capped type-II GaSb/GaAs quantum-rings at room temperature
(2013-09-01)
Lin, Wei-Hsun
;
Wang, Kai-Wei
;
Lin, Shih-Yen
;
Wu, Meng-Chyi
;
光電學院
The room-temperature photoluminescence (PL) and electroluminescence (EL) exceeding 1.3 mu m are observed for InGaAs-capped GaSb quantum-ring (QR) structures. With increasing In composition, the emission wavelength would shift from 1.18 to 131 mu m. The InGaAs-capped GaSb QRs also exhibit a higher injection current and stronger EL intensity at the same applied voltage. With the observation of low-temperature PL spectra, the transition mechanisms of the standard and InGaAs-capped QRs are further investigated. (c) 2012 Elsevier B.V. All rights reserved.
Temperature-dependent photoluminescence and carrier dynamics of standard and coupled type-II GaSb/GaAs quantum rings
(2013-09-01)
Lin, Wei-Hsun
;
Wang, Kai-Wei
;
Lin, Shih-Yen
;
Wu, Meng-Chyi
;
光電學院
Temperature-dependent photoluminescence (PL) and the corresponding carrier dynamics of standard and coupled type-II GaSb/GaAs quantum rings (QRs) are investigated in this article. Compared with standard QRs, the slower PL intensity decay of coupled QRs with increasing temperature is attributed to the depression of thermal quenching. More intense PL intensity is also observed for the coupled-QR sample at room temperature. With further reducing the GaAs spacer layer thickness to 2 nm, near two-times PL enhancement is observed. The results indicate that with the enhanced luminescence intensity of coupled-QR structure, type-II nano-structures may be utilized for light-emitting device applications. (c) 2013 Elsevier B.V. All rights reserved.
Heteroepitaxial growth of InN on GaN intermediate layer by PA-MOMBE
(2011-07-01)
Lai, Fang-I
;
Kuo, Shou-Yi
;
Chen, Wei-Chun
;
Lin, Woei-Tyng
;
Wang, Wei-Lin
In this paper, high-quality wurtzite indium nitride was epi-grown on sapphire substrates by plasma-assisted metal-organic molecule beam epitaxy system (PA-MOMBE). Structural and electrical properties of the InN films were significantly improved by employing a GaN buffer layer. In addition, high-resolution X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM), Hall Effect, Raman and photoluminescence spectroscopy were carried out to characterize the effect of the growth temperature on structural and optoelectronic properties. It was found that highly c-axis oriented InN epilayer can be obtained by optimizing growth conditions. TEM images reveal that the epitaxially grown InN/GaN interface is sharp, and the spacing of the InN(0 0 0 2) lattice plane is about 0.57 nm. Raman spectra also show a sharp peak at 491 cm(-1) attributed to the E(2)(high) mode of wurtzite InN. These results indicate that the improvement of InN material quality can be achieved using heteroepitaxy on GaN/sapphire templates. (C) 2011 Elsevier B.V. All rights reserved.

學術出版;;Publications

Browse

Filters

Settings

Sort By

Results per page

🏛️國立陽明交通大學機構典藏

Search Results